The invention relates to a closed-loop control method for operation of individually driven rotating machine elements with angle position control, which elements are coupled with a force fit or via a common load.
International application WO 97/11848 discloses a drive concept in which information which ensures synchronous angular running of the drives during rotation is transferred exclusively via a synchronization bus. Synchronous angular running of printing machines is required in order to achieve high production quality for the printed media.
If individually driven machine elements, which are mechanically coupled via a force fit or via a common load, are operated with angular position control, then different path speeds at the coupling point, path or medium lead to the occurrence of slip. The respective angular position control associated with the machine elements attempts to convert the preset values on the basis of the set value. In this case, it is possible for two drive regulators to produce control actions in opposite senses, that is to say one drive regulator attempts to drive, while another one attempts to brake. In this case, depending on the power relationships, slip occurs after the tear-free moment, during which slip the actual values of the machine elements which are involved change suddenly in the direction of the set values.
The mechanical loading of the drives and the occurrence of slip are associated with increased power requirements for the converters. This is normally taken into account in the design of the converter or drive itself.
The object of the invention is to eliminate or to minimize any position error for individually driven rotating machine elements which are operated using angular position control.
According to the invention, this object is achieved in that parameters which describe the circumference of the driven corresponding machine elements are supplied as a correction variable in the form of an angle position error to the input of the angle position regulator. In this case, geometric variables relating to rotating machine elements are included in the respectively involved drive regulators, and minimize the slip error. Even minor manufacturing tolerances in the rotating machine elements can be taken into account in a drive regulator by means of this method, thus improving the control accuracy. More accurate positioning is thus possible, as is required, for example, for machine tools and printing machines.
A further advantage of the described circumferential correction is that the power consumed by the converters involved is reduced considerably. The energy that was previously required for loading machine elements or for the occurrence of slip is considerably reduced, or is no longer required. In addition, the converters can be designed using the method according to the invention so that they require less energy.
A first advantageous embodiment of the invention is characterized in that diameters or radii of machine elements which are involved are used as paramters to describe the circumference. This allows easily accessible, measurable parameters of a rotating machine element to be configured in an advantageous manner in the respective drive regulators.
A further advantageous embodiment of the invention is characterized in that at least one diameter and at least one diameter difference, or at least one radius and at least one radius difference, are used as the parameters which describe the circumference. This method makes it easy to use measurement variables which can be determined from a relative measurement. For example, using this method, it is possible to use a main diameter or radius which is referred to in the control system by means of error details.
An advantageous device for operation of individually driven rotating machine elements using angle position control, which are coupled with a force fit or via a common load, is characterized in that parameters which describe the circumference of the driven corresponding machine elements can be supplied as a correction variable in the form of an angle position error to the input of the angle position regulator. This device advantageously makes it possible to eliminate or minimize a slip error in rotating machine elements or a driven load.
A control method as claimed in claims 1 to 3 and/or a device as claimed in claim 4 can advantageously be used in printing machines. The use of the closed-loop control method according to the invention and/or of the device according to the invention in a specific embodiment of production machines, namely printing machines, results in advantages. A higher-quality printed product can be produced by eliminating or minimizing the slip error.
A drive system such as this allows extremely high synchronization accuracies to be achieved between individually driven machine elements which are involved. Furthermore, electronically synchronized synchronization shafts, which are provided with high synchronization characteristics, and electronic transmissions can also be produced in a simple manner. Multi-color printing by rotary printing machines with individually driven printing cylinders, in particular, places particularly stringent requirements on the production accuracy of a printing machine.